re: 2x10, I ride a 2x10 with 28/39 rings and a 11-36 cassette. many trails in Kansas I can ride entirely in the big ring.

it depends on what you do with your MTB. if you ride it on fast road rides, then 2x10 may not work as well as a triple because most people don't buy the XC race cranksets with 39-42T big rings, and triples should have 42T or larger big rings. (hybrid triples often have 46 or 48.)

it also depends on how low of gearing you really need. for many people, a 22 or 24 granny ring on a triple is way overkill with a modern 34 or 36 cassette. you can walk way faster than 22x36, and in fact, it's so slow that some/most people would have difficulty maintaining their balance.

on a triple you probably ride most of the time in the middle ring, and have a lot of overlapped gears. but there's no doubt you have the widest total range which can be useful if you ride on the road (or pedal down long, smooth hills) and also would rather ride trials-style than get off and hike the steepest sections.

for me, I don't need a triple on a MTB. I have a cyclocross bike for gravel road rides, and a road bike for going fast on pavement. 39x11 gets me going pretty fast, anyway, especially on a big fat tire.